On 2013-12-11 Adam Thompson wrote:

LOL. That *is* a modem, only slowed down by about 10x and somewhat mangled. It sounds like a fax machine, to me.

Ya, it does sound like a fax handshake but with about 5-8 dropouts every second, and yes, probably slowed down.

Are you sure your homebrew voicemail and .wav conversion is working proeprly? Are you receiving voicemails that are similarly mangled? If you answered the phone at whatever a.m. when this comes in, it probably sounds like a normal fax (we're guessing)?

Are you using mgetty+vgetty for this? Converting from the weird vgetty/modem format to WAV and resampling isn't trivial, and perhaps a setting is wonky in there. You could try sending yourself a fax from somewhere at a known time and seeing if you get the same results.

PS: setting up vgetty to allow incoming faxes may also shed some light: at least you'd see what the fax is about!

On 2013-12-12 Daryl F wrote:

Ok. Wonder why the sender doesn't give up before five minutes?

If it's been slowed down, and gaps added that aren't really there in realtime, it might really be only 1-2 mins, which could be normal for an aggressive fax server.

Yes, the conversions are working properly for voicemails. It's been a great answering machine. I've been using it for years. Its an ISA card :)

I'd really love to see you put the config back to the way it was and have someone you know fax you at a known time. I'm sure someone in MUUG could do it, I know myself or Adam could send you a fax from home. At the very least it would immediately eliminate our theory if we're wrong. (After all, both aliens and SkyNet are still plausible theories.)

Yes, mgetty+vgetty is what I'm using. You've given me an idea. I checked the configuration and it set only for voice and no faxes. There's a compression setting for the modem voice output. Between that and the conversion from the native format coming from the Rockwell chipset it probably does explain the slow down and drop outs.

Sounds like your setup is nearly identical to mine, but I use an external Rockwell (Cardinal) modem. I remember the setup was very odd and tricky because the modem spits out bizarrely formatted audio files. Especially if you don't have baud rates perfectly matched you get strange audio problems both on your outgoing message and the incoming recording.

less /var/log/vgetty.log.ttyS0 (change the 0 to whatever you use) may show you exactly what the modem is doing at the time of the calls, in terms of the AT commands (and FAX commands). It may show you it is switching to the incorrect mode at strange times. The whole fax-receipt sequence of events is bizarre and somewhat mystical voodoo at the best of times!

I think I'll try that just for kicks. I'd have thought FAX spam was no more but we'll see.

No such luck! I get about 5 fax spams a day, mostly people trying to sell me metal warehouse buildings and self-help seminars for some strange reason.